Fish Oil for Muscle Growth and Prevention of Muscle Loss with Aging

A key hallmark of aging is a progressive loss of muscle mass, which occurs independently of health status.[1] Exercise and nutrition are the two main anabolic stimuli for muscle growth and its maintenance throughout the life course.[2-11]

It is clear that maintaining high physical activity and exercise levels throughout ones lifespan reduces aging related loss of muscle mass and function, compared with living a sedentary life.[12-19]

However, even active older adults and master elite athletes still experience some loss of muscle and physical performance with advancing age.[8, 13, 20]

When it comes to nutrition, high protein intake [2, 3, 10, 21] and creatine supplementation [4-8, 22] are two of the best documented interventions, which together with resistance exercise training, result in greater increases muscle mass and strength in both young [21-23] and older people [2-8, 10], and prevent its loss with aging. Here I will present the relatively unknown effevts of fish oil (most well-known for its cardiovascular health promoting effects) on muscle growth (anabolism) and its possible contribution to prevention of aging related loss of muscle mass and function...

Increased Muscle Growth with Fish Oil

Several studies therefore directly investigated the effect of fish oil on metabolic pathways that underlie muscle growth, with very interesting findings....

Supplementing healthy young and middle-aged (25-45 year old) men and women with 4 g per day of fish oil concentrate - providing a daily dose of 1.86 g EPA and 1.5 g DHA – for 8 weeks was found to significantly increase the anabolic response of muscle protein synthesis to amino acids and insulin.[24] The augmented anabolic response to amino acids and insulin was shown to be due to an increased activation of the mTOR/p70S6K signaling pathway, which is considered an integral control point for muscle protein anabolism [25] and muscle cell growth.[26-29]

Other mechanisms probably contribute as well. The same study showed that the fish oil supplementation doubled the proportion of EPA, DPA (another less well known omega-3 fatty acid) and DHA in muscle cell membranes, at the expense of omega-6 fatty acids and mono-unsaturated fatty acids, with no change in saturated fatty acid concentrations.[24] Thus, it is possible that fish oil supplementation may influence anabolic signaling cascades by affecting membrane lipid composition and/or fluidity.[30-33]

Fish oil supplementation also confers muscle anabolic effects in the elderly. The same research team conducted another study, using an identical research protocol (1.86 g EPA and 1.5 g DHA for 8 weeks), in healthy elderly subjects over 65 years (mean age 71 years).[34] The results were the same as in the younger subjects [24]; fish oil supplementation significantly increased the muscle protein synthetic response to amino acids and insulin.[34] Thus, fish oil seems to attenuate the anabolic resistance to protein intake that develops with aging.[35-37] The researchers were so impressed with this response that they concluded high dose fish oil may be useful for both prevention and treatment of sarcopenia.[34] Support for this comes from a study specifically demonstrating that fish oil increases anabolic signaling in aged muscles.[38]

Both of these studies only measured the response of muscle protein synthesis to amino acids and insulin.[24, 34] Muscle mass, which is the result of a net positive muscle protein balance over a longer time period (at least 6 months), was not measured because the interventions lasted for only 8 weeks. However, taking into consideration that changes in muscle protein metabolism precede corresponding changes in muscle mass [39-41], these results are very promising.

Indeed, recently longer term outcomes of the fish oil supplementation study in elderly were published.[42] Compared with the placebo group (which were given identical soft gels containing corn oil), supplementing healthy elderly subjects with 1.86 g EPA and 1.5 g DHA for 6 months significantly increased thigh muscle volume by 3.6%, handgrip strength by 2.3 kg (5.1 lb), 1-RM muscle strength by 4.0%. There was also a trending increase in power output by 5.6% in the fish oil group.[42]

The difference in muscle volume between the fish oil and the placebo group at 6 mo was +3.5%, and the difference in overall muscle strength was +6%.[42] This suggests that 6 month of fish oil supplementation can prevent 2-3 years of normal age-related losses in muscle mass (0.5–1.0%/year) and function (w2–3%/year).[43-46] Thus, it was concluded that the fish oil fatty acids EPA and DHA may slow the common age-related decline in muscle mass and function in older adults, and that fish oil should be considered a therapeutic approach for preventing sarcopenia and maintaining physical independence in older adults.[42]

Decreased Muscle Breakdown with Fish Oil

Another way that fish oil can promote muscle growth is by exerting anti-catabolic effects. Muscle growth occurs during periods of positive net muscle protein balance, that is, when muscle protein synthesis exceeds muscle protein breakdown. Muscle proteins undergo a continuous process of synthesis (anabolism) and breakdown (catabolism). In a healthy state, the anabolic and catabolic processes are balanced to maintain stability, or an increase muscle mass (as is observed with resistance training combined with proper nutrition and supplementation).

Catabolism of muscle tissue is common in both clinical states (for example diabetes, renal failure, trauma and cancer) and during dieting and other stress conditions [47-52]. During these catabolic states, muscle protein degradation (catabolism) exceeds muscle protein synthesis (anabolism), which results in muscle loss and weakness.

Muscle protein catabolism is primarily caused by the ubiquitin-proteasome system [49, 52-57]. It is here fish oil enters the picture, since its fatty acid EPA significantly decreases the activity of the muscle protein catabolic (ubiquitin-proteasome) system.[48, 50, 51, 58-62]

An additional mechanism by which fish oil may exert its anti-catabolic effect is by reducing cortisol levels.[63, 64] Cortisol breaks down muscle tissue [65] and contributes a host of other detrimental health effects when present at chronically elevated levels (which is a topic for another article).[66-68] Thus, the cortisol lowering is a beneficial effect of fish oil beyond anti-catabolism.

When it comes to prevention of muscle loss with aging, a paramount question is whether the beneficial muscle anabolic and anti-catabolic effects seen in short term studies translate into physical performance enhancements? Several long-term studies show promising results.

One study in postmenopausal women found long-term (6 months) fish oil supplementation (providing 1.2g EPA + DHA]) to improve physical performance indices (such as walking speed) compared to placebo (olive oil).[69] Moreover, during a 90-day resistance exercise training program in older women, the consumption of fish oil supplements (2 g per day) resulted in greater gains in muscle strength and functional capacity when compared with a placebo.[70] And as outlined above, long term fish oil supplementation increases not only thigh muscle volume, but also muscle strength as well as power output.[42]

More and more studies show that the anabolic effects of nutrients (e.g. amino acids or proteins), hormones (e.g. insulin, testosterone) and/or exercise on muscle can be enhanced by long-term fish oil supplementation.[71] A recent review of the research literature concluded that long-term fish oil supplementation, in association with anabolic stimuli like exercise and proper nutrition, could potentially provide a safe, simple and low-cost intervention to counteract anabolic resistance and aging related loss of muscle mass, strength and performance.[71]

Conclusion

In a previous article “Muscles – not just for bodybuilders!” I explained that, contrary to mainstream attitudes, muscles aren’t just for show. Your muscle mass contributes to your physical and metabolic health, which in turn paves the way for multiple health benefits.

Research shows that fish oil supplementation in both young and older adults increases muscle protein synthesis in response to anabolic stimuli like exercise and protein intake. In addition, fish oil may inhibit breakdown of muscle tissue. Together, over time, the fish oil induced stimulation of muscle protein synthesis (anabolism) and inhibition of muscle protein breakdown (catabolism) will increase net muscle protein balance and muscle mass, and possibly also strength and performance.

Aim for a daily fish oil intake that provides at least 1900 mg (1.9 g) EPA and 1500 mg (1.5 g) DHA. Ideally, strive to get at minimum about 2000 mg of each, i.e. 2000 mg EPA and 2000 mg DHA = 4000 mg (4 g) total. At of this writing, there is not enough research data to make precise recommendations on any specific EPA-to-DHA ratio for muscle growth and strength gains.

Remember to read the labels as different fish oil products provide different amounts of EPA and DHA. Don’t buy low quality fish oil products that do not specify the content of EPA and DHA individually. Look for a fish oil concentrate that provides over 50% EPA and DHA of the total fat content.

By adding fish oil supplementation to your daily regimen you will not only reap muscle related benefits, but also a range of other health benefits (which I will cover individually in upcoming articles):

* Increased fat burning and fat loss.[59, 67-73] This, together with stimulation of muscle anabolism and reduction of muscle catabolism, will contribute to improvement of body composition and related health parameters.